High-frequency magnetic field generating device

ABSTRACT

A high-frequency magnetic field generating device includes two coils arranged with a predetermined gap in parallel with each other, the two coils (a) in between which electron spin resonance material is arranged or (b) arranged at one side from electron spin resonance material; a high-frequency power supply that generates microwave current that flows in the two coils; and a transmission line part connected to the two coils, that sets a current distribution so as to locate the two coils at positions other than a node of a stationary wave.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 16/103,356, filed on Aug. 14, 2018, which relates to and claimspriority rights from (1) Japanese Patent Application No. 2017-174895,filed on Sep. 12, 2017 and (2) Japanese Patent Application No.2018-038182, filed on Mar. 5, 2018, the entire disclosures of which arehereby incorporated by reference herein.

BACKGROUND Technical Field

The present invention relates to a high-frequency magnetic fieldgenerating device.

Background Art

In Optically Detected Magnetic Resonance (ODMR), a medium that hassublevels and an optical transition level as energy level issimultaneously irradiated with a high-frequency magnetic field(microwave) and light, and thereby a population change or the like dueto magnetic resonance between the sublevels is detected as an opticalsignal with high sensitivity.

In general, after an electron in a ground state is excited with greenlight, the electron emits red light when returning the ground state.Contrarily, for example, when an electron is irradiated with ahigh-frequency magnetic field of about 2.87 GHz in a nitrogen and alattice defect in a diamond structure (NVC: Nitrogen Vacancy Center),the electron moves from the lowest level (ms=0) among three sublevels ofthe ground state to an energy level (ms=+1 or −1) higher than the lowestlevel among the three sublevels. When the electron in such state isirradiated with green light, an emitting light intensity is decreasedbecause of no radiation transition to the lowest level (ms=0) among thethree levels of the ground level; and therefore, it can be determined bydetecting this light whether magnetic resonance occurs due to thehigh-frequency magnetic field. As mentioned, in ODMR, optically detectedmagnetic resonance material such as NVC is used.

In a measurement system, a split-ring resonator or an antenna of a coilor wire type is arranged under a diamond sample, and the resonator orthe like irradiates the sample with a high-frequency magnetic field in amicrowave range of about 2.87 GHz, and while the high-frequency magneticfield and the exciting light are swept, a detection device detects aposition at which the red light from an electron decreases and therebyinformation on a cell near the aforementioned diamond structure isacquired (for example, see NON-PATENT LITERATURE #1).

Further, a magnetic measurement device performs magnetic measurementbased on ODMR using electron spin resonance (for example, see PATENTLITERATURE #1). In this magnetic measurement device, as well, a magneticfield as micro wave is generated with only one coil.

CITATION LIST Patent Literature

-   PATENT LITERATURE #1: Japanese patent application publication    2012-110489.

Non-Patent Literature

-   NON-PATENT LITERATURE #1: Kento Sasaki, et. al., “Broadband,    large-area microwave antenna for optically-detected magnetic    resonance of nitrogen-vacancy centers in diamond”, REVIEW OF    SCIENTIFIC INSTRUMENTS 87, 053904 (2016).

SUMMARY Technical Problem

However, the aforementioned coil or antenna is capable of generating athree-dimensional uniform high-frequency magnetic field only in a verynarrow range, and therefore high detection sensitivity of ODMR is hardlyachieved. For example, in case of NON-PATENT LITERATURE #1, as shown inFIG. 20, a ring-antenna resonator is used that is a circular copperplate with a radius R (about 7 mm), and a slit is formed at the centerof the plate and further a penetrating hole with a radius r (about 0.5mm) is formed at a tip of the slit. A high-frequency power supplyprovides current with about 2.87 GHz to the resonator, and thereby, asshown in FIG. 21, although a uniform magnetic field is generated at anarea within a 1-mm radius from the center, the magnetic field intensitygradually decreases along a radius direction from the center of the coilin the other area, i.e. that is 98 percent of the area of the copperplate; and therefore, this area can not be used for the detection basedon ODMR. It should be noted that the same problem arises in anothermeasurement using electron spin resonance such as Electrically DetectedMagnetic Resonance (EDMR).

The present invention is conceived in view of the aforementionedproblem, and provides a high-frequency magnetic field generating devicethat generates a substantially uniform high-frequency magnetic field ina wide three dimensional range and improves detection sensitivity inmeasurement based on electron spin resonance.

Solution to Problem

A high-frequency magnetic field generating device according to thepresent invention includes two coils arranged with a predetermined gapin parallel with each other, the two coils (a) in between which electronspin resonance material is arranged or (b) arranged at one side fromelectron spin resonance material; a high-frequency power supply thatgenerates microwave current that flows in the two coils; and atransmission line part connected to the two coils, that sets a currentdistribution so as to locate the two coils at positions other than anode of a stationary wave.

A high-frequency magnetic field generating device according to thepresent invention includes a high-frequency power supply; at least twopairs of coils; and at least two transmission lines that include (a) atransmission line in between (a1) one coil in one pair among the twopairs and (a2) one coil in the other pair among the two pairs and (b) atransmission line in between (b1) the other coil in the one pair amongthe two pairs and (b2) the other coil in the other pair among the twopairs. The high-frequency power supply generates microwave current thatflows in two coils that form each pair among the at least two pairs.Further, the two coils that form each pair among the at least two pairsare arranged with a predetermined gap in parallel with each other, thetwo coils (a) in between which electron spin resonance material isarranged or (b) arranged at one side from electron spin resonancematerial. Furthermore, the at least two transmission lines set a currentdistribution so as to locate the coils in the at least two pairs atpositions other than a node of a stationary wave.

A high-frequency magnetic field generating device according to thepresent invention includes a circuit board; a penetrating hole in thecircuit board; a plate coil arranged in the penetrating hole; ahigh-frequency power supply that generates microwave current that flowsin the plate coil; and a transmission line part connected to the platecoil, that sets a current distribution so as to locate the plate coil ata position other than a node of a stationary wave. Further, alongitudinal direction of a cross section of the plate coil isperpendicular to the circuit board. Furthermore, (a) one edge line partin a top end side and (b) one edge line part in a bottom end side amongfour edge line parts of the plate coil act as two coils arranged with apredetermined gap in parallel with each other, the two coils (a) inbetween which electron spin resonance material is arranged or (b)arranged at one side from electron spin resonance material.

Advantageous Effects of Invention

The present invention provides a high-frequency magnetic fieldgenerating device that generates a substantially uniform high-frequencymagnetic field in a wide three dimensional range and improves detectionsensitivity in measurement based on electron spin resonance.

These and other objects, features and advantages of the presentdisclosure will become more apparent upon reading of the followingdetailed description along with the accompanied drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view diagram that explains an arrangement ofcoils in a high-frequency magnetic field generating device in anembodiment of the present invention;

FIG. 2 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 1 of thepresent invention;

FIG. 3 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 2 of thepresent invention;

FIG. 4 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 3 of thepresent invention;

FIG. 5 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 4 of thepresent invention;

FIG. 6 shows a perspective view diagram that explains an example of anarrangement of coils in a high-frequency magnetic field generatingdevice in Embodiment 4 of the present invention;

FIG. 7 shows a perspective view diagram that explains an example of anarrangement of coils and line units in a high-frequency magnetic fieldgenerating device in Embodiment 5 of the present invention;

FIG. 8 shows a perspective view diagram that explains an example of anarrangement of coils and line units in a high-frequency magnetic fieldgenerating device in Embodiment 6 of the present invention;

FIG. 9 shows a perspective view diagram that explains another example ofline units in a high-frequency magnetic field generating device inEmbodiment 6 of the present invention;

FIG. 10 shows a perspective view diagram that explains an example of anarrangement of coils and line units in a high-frequency magnetic fieldgenerating device in Embodiment 7 of the present invention;

FIG. 11 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 8 of thepresent invention;

FIG. 12 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in a modificationexample #1 of Embodiment 8 of the present invention;

FIG. 13 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in a modificationexample #2 of Embodiment 8 of the present invention;

FIG. 14 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 9 of thepresent invention;

FIG. 15 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 10 of thepresent invention;

FIG. 16 shows a diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 11 of thepresent invention;

FIG. 17 shows a diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 12 of thepresent invention;

FIG. 18 shows a diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 13 of thepresent invention;

FIG. 19 shows a diagram that indicates a result of a simulation of amagnetic field emitted from the high-frequency magnetic field generatingdevice in Embodiment 6 of the present invention;

FIG. 20 shows a circuit diagram that indicates a configuration of anordinary coil-type high-frequency generating device; and

FIG. 21 shows a diagram that indicates a magnetic field emitted from anordinary coil-type high-frequency generating device.

DETAILED DESCRIPTION

Hereinafter, embodiments according to aspects of the present inventionwill be explained with reference to drawings.

Embodiment 1

FIG. 1 shows a perspective view diagram that explains an arrangement ofcoils in a high-frequency magnetic field generating device in anembodiment of the present invention.

The high-frequency magnetic field generating device in an embodiment ofthe present invention includes at least two coils L1 and L2. As shown inFIG. 1, the two coils L1 and L2 are arranged with a predetermined gap(e.g. substantially equal to a diameter of the coils L1 and L2) inparallel with each other. Further, a sample 101 is arranged on a platemember 102 such as diamond that includes an NVC as Optically DetectedMagnetic Resonance material (hereinafter, called ODMR material), and theplate member 102 is fixed on a sample plate 103. Furthermore, the twocoils L1 and L2 are arranged such that the plate member 102 including anNVC as the ODMR material is arranged in between the two coils L1 and L2.The ODMR material is a sort of electron spin resonance material.

The two coils L1 and L2 have identical shapes to each other, and arearranged so as to have identical central axes to each other. Here, thenumber of turns of each coil L1 or L2 is set as substantially one turn(less than one turn). In the two coils L1 and L2, microwave currentflows, and the two coils L1 and L2 generate alternate magnetic fields asmicrowaves in phase with each other (i.e. toward identical directions toeach other at each time point), respectively. The alternate magneticfields are applied to the ODMR material, and in addition to thealternate magnetic fields generated by the coils L1 and L2, a staticmagnetic field (not shown) is applied to the ODMR material. Further,using an optical system (not shown), the ODMR material is irradiatedwith a measurement light such as laser light beam of a predeterminedwavelength, and a measurement based on Optically Detected MagneticResonance (e.g. magnetic measurement, orientation measurement of an NVC,temperature measurement of an NVC or the like) is performed, forexample, by observing radiant light having a specific wavelength.

FIG. 2 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 1 of thepresent invention.

As shown in FIG. 2, the high-frequency magnetic field generating devicein Embodiment 1 further includes a high-frequency power supply 1, andtwo line units S1 and S2.

The high-frequency power supply 1 generates microwave current that flowsin the two coils L1 and L2. Specifically, the high-frequency powersupply 1 generates the microwave current in a frequency band requiredfor the Optically Detected Magnetic Resonance (here, about 2.87 GHz).

The two line units S1 and S2 form a transmission line part respectivelyconnected to the two coils L1 and L2, and set a current distribution soas to locate the two coils L1 and L2 at positions other than a node of astationary wave.

Each of the line units S1 and S2 may be formed as one conductive wireline or as a distributed constant circuit including a resister element,a condenser element and/or the like.

Specifically, in Embodiment 1, as shown in FIG. 2, one-side ends of thetwo line units S1 and S2 are open-circuited, and other-side ends of thetwo line units S1 and S2 are connected to one-side ends of the two coilsL1 and L2, respectively. Further, other-side ends of the two coils L1and L2 are electrically connected to each other, and the high-frequencypower supply 1 is connected to a connecting point between the other-sideends of the two coils L1 and L2. Therefore, microwave current flows fromthe high-frequency power supply 1 into the other-side ends of the twocoils L1 and L2. The two coils L1 and L2 have identical shapes to eachother, and the line units S1 and S2 also have identical shapes to eachother. Consequently, in view from the high-frequency power supply 1, (a)the coil L1 and the line unit S1 and (b) the coil L2 and the line unitS2 have identical high frequency characteristics (i.e. identicalelectrical lengths) to each other.

For example, if both (a) an electrical length of the coil L1 and theline unit S1 and (b) an electrical length of the coil L2 and the lineunit S2 are LAMBDA/4 (LAMBDA: wavelength of the microwave), then acurrent distribution as shown in FIG. 2 appears, and the coils L1 and L2are not located at any nodes of a stationary wave but located nearantinodes of a stationary wave; and consequently, sufficient microwavecurrent flows in the coils L1 and L2 and induces a magnetic field as amicrowave.

For example, if the high-frequency power supply 1 generates a microwaveof 2.87 GHz, then the wavelength is about 10 cm, and therefore, theelectrical length of the coil L1 and the line unit S1 and the electricallength of the coil L2 and the line unit S2 are set as about 2.5 cm. Inaddition, for easy tuning, it is favorable that lengths of the coils L1and L2 are set to be shorter than a half of lengths of the line units S1and S2.

The following part explains a behavior of the high-frequency magneticfield generating device in Embodiment 1.

When the high-frequency power supply 1 generates a microwave asalternate power, microwave current flows into (a) the coil L1 and theline unit S1 and (b) the coil L2 and the line unit S2. Here, since theimpedance is matched for the whole circuit, there is no need to use animpedance matching unit separately at a terminal end of (a) the coil L1and the line unit S1 and at a terminal end of (b) the coil L2 and theline unit S2, and a stationary wave as shown in FIG. 2 is formed in (a)the coil L1 and the line unit S1 and (b) the coil L2 and the line unitS2.

Consequently, in the coils L1 and L2, alternate current flows withidentical amplitude to each other in phase with each other. A magneticfield as microwave is formed by the current that flows in the coils L1and L2. Further, the coils L1 and L2 are arranged coaxially andsubstantially in parallel with each other, and therefore, in a spacebetween the coil L1 and the coil L2, a direction of the magnetic fieldis substantially in parallel with a central axis of the coils L1 and L2and the magnetic field is substantially uniform.

As mentioned, in Embodiment 1, the two coils L1 and L2 are arranged witha predetermined gap in parallel with each other and in between the twocoils L1 and L2 electron spin resonance material is arranged. Thehigh-frequency power supply 1 generates microwave current that flows inthe two coils L1 and L2. The two line units S1 and S2 are connected tothe two coils L1 and L2, respectively, and set a current distribution soas to locate the two coils L1 and L2 at positions other than a node of astationary wave.

Consequently, a substantially uniform high-frequency magnetic field isgenerated in a wide three dimensional range in between the coils L1 andL2. Consequently, detection sensitivity of ODMR can be improved.

In this embodiment, the one-side ends of the line units S1 and S2 areopen-circuited. Alternatively, for example, high impedance circuitshaving a high impedance sufficiently for a frequency of the microwavecurrent (i.e. oscillation frequency of the power supply) may beconnected to these open-circuited one-side ends and a ground.

Further, as shown in FIG. 1, the two coils L1 and L2 are arranged with apredetermined gap in parallel with each other such that ODMR material isarranged in between the two coils L1 and L2. Alternatively, both of thetwo coils L1 and L2 may be arranged at one side from the electron spinresonance material. In such a case, although resonance band width gets alittle narrow, arrangement position of the ODMR material gets highflexibility.

Furthermore, in FIG. 1, the plate member 102 and the sample plate 103are arranged to be perpendicular to the direction of the magnetic field(i.e. the direction of the central axis of the coils L1 and L2).Alternatively, the plate member 102 and the sample plate 103 may bearranged to be slanted to the direction of the magnetic field (i.e. thedirection of the central axis of the coils L1 and L2). Even in such acase, the uniform magnetic field is applied to the plate member 102.

Embodiment 2

FIG. 3 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 2 of thepresent invention. The high-frequency magnetic field generating devicein Embodiment 2 has the same configuration as the configuration of thehigh-frequency magnetic field generating device in Embodiment 1, andadditionally includes an impedance matching unit 11 in between thehigh-frequency power supply 1 and the two coils L1 and L2.

If impedance matching is not achieved in between the high-frequencypower supply 1 and the two coils L1 and L2, then a microwave from thehigh-frequency power supply 1 reflects at the coils L1 and L2, andconsequently adequate microwave current does not flow into the coils L1and L2. Therefore, if impedance matching is not achieved in between thehigh-frequency power supply 1 and the two coils L1 and L2, then theimpedance matching unit 11 is installed. Consequently, the impedancematching is achieved and the microwave from the high-frequency powersupply 1 propagates into the coils L1 and L2. As the impedance matchingunit 11, for example, a resistance element (R), a capacitance element(C), an inductance element (L) or a combination thereof is used.

In FIG. 3, the impedance matching unit 11 is installed in between thehigh-frequency power supply 1 and a connecting point between the coilsL1 and L2. Alternatively, two impedance matching units 11 may beinstalled (a) in between the high-frequency power supply 1 and the coilL1 and (b) in between the high-frequency power supply 1 and the coil L2,respectively.

Further, in a high-frequency magnetic field generating device in anotherembodiment mentioned below, the same impedance matching unit(s) may beinstalled as well. If the high-frequency power supply 1 is connected totwo line units in another embodiment, the impedance matching unit(s) maybe installed in between the high-frequency power supply 1 and the twoline units in the same manner.

As mentioned, in Embodiment 2, even when the impedance matching is notachieved with only the coils L1 and L2 and the line units S1 and S2, theimpedance matching can be achieved by the impedance matching unit 11.

Embodiment 3

FIG. 4 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 3 of thepresent invention. The high-frequency magnetic field generating devicein Embodiment 3 includes at least two pairs of coils (L1-i, L2-i) (i=1,. . . , n; n>1) and at least two line units S1-j, S2-j that include (a)a line unit S1-j in between (a1) one coil L1-i in one pair among the atleast two pairs and (a2) one coil L1-i in the other pair among the atleast two pairs and (b) a line unit S2-j in between (b1) the other coilL2-i in the one pair among the at least two pairs and (b2) the othercoil L2-i in the other pair among the at least two pairs.

In Embodiment 3, the high-frequency power supply 1 generates microwavecurrent that flows two coils L1-i and L2-i that form each pair among theaforementioned at least two pairs of coils (L1-i, L2-i).

The two coils that form each pair among the aforementioned at least twopairs of coils (L1-i, L2-i) are arranged with a predetermined gap inparallel with each other, and electron spin resonance material isarranged in between these two coils. For example, the coils L1-1 to L1-nare arranged such that the magnetic fields induced by the coils L1-1 toL1-n gets in phase with each other, and the coils L2-1 to L2-n arearranged such that the magnetic fields induced by the coils L2-1 to L2-ngets in phase with each other. Thus, the magnetic fields induced by thecoils L1-1 to L1-n and L2-1 to L2-n have identical directions to eachother.

Further, the aforementioned at least two line units S1-j and S2-j as atransmission line unit set a current distribution so as to locate thecoils L1-i and L2-i in the at least two pairs at positions other than anode of a stationary wave. For example, all of the line units S1-j andS2-j have identical electric lengths with each other, the line unitsS1-j and the coils L1-j are alternately arranged, and the line unitsS2-j and the coils L2-j are alternately arranged. Specifically, the lineunit S1-j is arranged in between the coil L1-j and the coil L1-(j+1),the line unit S2-j is arranged in between the coil L2-j and the coilL2-(j+1), and a terminal end of the line unit S1-n and a terminal end ofthe line unit S2-n are open-circuited.

For example, the coils L1-i and L2-i have identical shapes to each otherand are arranged so as to have identical central axes to each other.Here, the number of turns of each coil L1-i or L2-i is set assubstantially one turn (less than one turn); and if both (a) anelectrical length of the coils L1-1 to L1-n and the line unit(s) S1-jtherebetween and (b) an electrical length of the coil L2-1 to L2-n andthe line unit(s) S2-j therebetween are (2 n−1)*LAMBDA/4, then a currentdistribution as shown in FIG. 4 appears, and all of the coils L1-i andL2-i are located at positions other than any nodes of a stationary wave;and consequently, sufficient microwave current flows in the coils L1-iand L2-i and induces a magnetic field as a microwave.

As mentioned, in Embodiment 3, a large number of the coils L1-i and L2-iare installed. Consequently, the induced high-frequency magnetic fieldgets a high intensity.

Embodiment 4

FIG. 5 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 4 of thepresent invention. As shown in FIG. 5, the high-frequency magnetic fieldgenerating device in Embodiment 4 includes two pairs of coils (L11, L21)and (L12, L22), and two line units S11 and S21 as a transmission linepart.

FIG. 6 shows a perspective view diagram that explains an example of anarrangement of the coils L11, L12, L21 and L22 in a high-frequencymagnetic field generating device in Embodiment 4 of the presentinvention. As shown in FIG. 6, the number of turns of each coils L11,L21, L12 or L22 is substantially a half of one turn; and the coil L11and the coil L22 form a pair and induce magnetic fields as microwave inphase with each other, and the coil L12 and the coil L21 form a pair andinduce magnetic fields as microwave in phase with each other.

Alternatively, the number of turns of each coils L11, L21, L12 or L22may be substantially one turn as well as in Embodiment 1, 2 or 3; andthe in-phase coils L11 and L22 may be arranged contiguously to eachother (i.e. so as to cause the number of turns to get substantially twoturns in total), and the in-phase coils L12 and L21 may be arrangedcontiguously to each other.

Further, in Embodiment 4, (a) one-side ends of the two coils L12 and L22are connected to a ground, (b) other-side ends of the two coils L12 andL22 are connected to one-side ends of the two line units S11 and S21,(c) other-side ends of the two line units S11 and S21 are connected toone-side ends of the two coils L11 and L21, (d) other-side ends of thetwo coils L11 and L21 are connected to each other, and (e) thehigh-frequency power supply 1 is connected to a connecting positionbetween the two coils L11 and L21. Microwave current flows from thehigh-frequency power supply 1 through the coils L11 and L21 into theother-side ends of the two line units S11 and S21. Therefore, antinodesof the current distribution are located at ends (i.e. short-circuitedends) of the coils L12 and L22, and as shown in FIG. 5, each of thecoils L11, L12, L21 and L22 is located at a position other than a nodeof the current distribution.

Embodiment 5

FIG. 7 shows a perspective view diagram that explains an example of anarrangement of coils and line units in a high-frequency magnetic fieldgenerating device in Embodiment 5 of the present invention.

The high-frequency magnetic field generating device in Embodiment 5 hasa circuit configuration as described in Embodiment 1 or 2 (i.e. FIG. 2or 3), and includes a circuit board 21. The two coils L1 and L2 arearranged on one surface of the circuit board 21 so as to besubstantially perpendicular to this surface. Further, in Embodiment 5,the two line units S1 and S2 are line members that havepartially-cutted-off ring shapes and are arranged on the other surfaceof the circuit board 21 so as to be substantially perpendicular to thissurface.

Furthermore, in the manner shown in FIG. 2 or 3, the coils L1 and L2,the line units S1 and S2, and the high-frequency power supply 1 areelectrically connected, and these electrical connections are establishedwith a wiring pattern on the circuit board 21, a through hole in thecircuit board 21, and/or the like.

Behaviors of the high-frequency magnetic field generating device inEmbodiment 5 are identical or similar to those in Embodiment 1 or 2, andtherefore not explained here.

Embodiment 6

FIG. 8 shows a perspective view diagram that explains an example of anarrangement of coils and line units in a high-frequency magnetic fieldgenerating device in Embodiment 6 of the present invention.

The high-frequency magnetic field generating device in Embodiment 6 hasa circuit configuration as described in Embodiment 1 or 2 (i.e. FIG. 2or 3), and includes a circuit board 21. The two coils L1 and L2 arearranged on one surface of the circuit board 21 so as to besubstantially perpendicular to this surface. Further, in Embodiment 6,the two line units S1 and S2 are wiring patterns, respectively, and areformed on any surface of the circuit board 21.

FIG. 9 shows a perspective view diagram that explains another example ofline units in a high-frequency magnetic field generating device inEmbodiment 6 of the present invention. As shown in FIG. 9, branch parts31 and 32 identical to each other are formed in the line units S1 andS2, respectively. Consequently, using the branch parts 31 and 32, thecurrent distribution can be adjusted in the coils L1 and L2 and the lineunits S1 and S2, and in addition, a width of input frequency band can beadjusted.

Behaviors of the high-frequency magnetic field generating device inEmbodiment 6 are identical or similar to those in Embodiment 1 or 2, andtherefore not explained here.

Embodiment 7

FIG. 10 shows a perspective view diagram that explains an example of anarrangement of coils and line units in a high-frequency magnetic fieldgenerating device in Embodiment 7 of the present invention.

The high-frequency magnetic field generating device in Embodiment 7 hasa circuit configuration as described in Embodiment 4 (i.e. FIG. 5), andincludes a circuit board 21. As shown in FIG. 10, in Embodiment 7, thecoils L11, L12, L21 and L22 are arranged on the circuit board 21 so asto be perpendicular to the circuit board 21, the line unit S11 that hasa partially-cutted-off ring shape is connected to an end of the coil L11and an end of the coil L12, and the line unit S21 that has apartially-cutted-off ring shape is connected to an end of the coil L21and an end of the coil L22.

As shown in FIG. 10, the line units S11 and S21 are arranged so as to beperpendicular to an opening direction of the coils L11 and L22 and anopening direction of the coils L12 and L21 (i.e. a direction of amagnetic field formed by the coils L11, L22, L12 and L21), such thatmagnetic coupling is restrained between (a) the coils L11, L22, L12 andL21 and (b) the line units S11 and S2.

Behaviors of the high-frequency magnetic field generating device inEmbodiment 7 are identical or similar to those in Embodiment 4, andtherefore not explained here.

Embodiment 8

FIG. 11 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 8 of thepresent invention.

In the high-frequency magnetic field generating device in Embodiment 8,as shown in FIG. 11, the two coils L1 and L2 are connected in parallelwith each other, and one transmission line S1 s as a transmission linepart is connected to a connecting point between the two coils L1 and L2.In Embodiment 8, the one transmission line S1 s sets a currentdistribution so as to locate the two coils L1 and L2 at positions otherthan a node of a stationary wave.

Specifically, in Embodiment 8, as shown in FIG. 11, one end of the lineunit S1 s is open-circuited, and the other end of the line unit S1 s isconnected to one connecting point between the two coils L1 and L2.Further, the high-frequency power supply 1 is connected to the otherconnecting point between the two coils L1 and L2. Therefore, microwavecurrent flows from the high-frequency power supply 1 into the other-sideends of the two coils L1 and L2. The two coils L1 and L2 have identicalshapes to each other. Consequently, in view from the high-frequencypower supply 1, (a) the coil L1 and the line unit S1 s and (b) the coilL2 and the line unit S1 s have identical high frequency characteristics(i.e. identical electrical lengths) to each other.

For example, if an electrical length of the coils L1 and L2 and the lineunit S1 s is LAMBDA/4 (LAMBDA: wavelength of the microwave), then acurrent distribution as shown in FIG. 11 appears, and the coils L1 andL2 are not located at any nodes of a stationary wave but located nearantinodes of a stationary wave; and consequently, sufficient microwavecurrent flows in the coils L1 and L2 and induces a magnetic field as amicrowave.

Behaviors of the high-frequency magnetic field generating device inEmbodiment 8 are identical or similar to those in Embodiment 1, andtherefore not explained here.

In Embodiment 8, instead of the configuration of the high-frequencymagnetic field generating device shown in FIG. 11, modification examplesshown in FIG. 12 or 13 may be applied.

FIG. 12 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in a modificationexample #1 of Embodiment 8 of the present invention. In the modificationexample #1 shown in FIG. 12, one end of a variable capacitance element41 is connected to one end of the line unit S1 s such that this one endis not connected to the coils L1 and L2, and the other end of thevariable capacitance element 41 is connected to a ground. Consequently,even if displacement appears between the central axes, a center of aresonance frequency band of the coils L1 and L2 can be adjusted bychanging a capacitance of the variable capacitance element 41 so as tocause the center of a resonance frequency band to get closest to adesired frequency. A very small capacitance value is sufficient of thisvariable capacitance element 41. Therefore, the variable capacitanceelement 41 may be a device that moves a position of a part of the lineunit S1 s a little. Alternatively, the variable capacitance element 41may be a variable capacitor that has a small capacitance, for example.

FIG. 13 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in a modificationexample #2 of Embodiment 8 of the present invention. In the modificationexample #2 shown in FIG. 13, one end of a variable capacitance element51 is connected to one-side ends (i.e. the ends on the power supplyside) of the coils L1 and L2 such that the one-side ends are notconnected to the line unit S1 s, and the other end of the variablecapacitance element 51 is connected to a ground. Consequently, as wellas the aforementioned modification example #1, even if shapes of thecoils L1 and L2 change or displacement occurs between the central axes,a center of a resonance frequency band of the coils L1 and L2 can beadjusted by changing a capacitance of the variable capacitance element51 so as to cause the center of a resonance frequency band to getclosest to a desired frequency. A very small capacitance value issufficient of this variable capacitance element 51. Therefore, thevariable capacitance element 51 may be (a) a variable capacitor that hasa small capacitance, for example, (b) a device that moves a part of aconductive line between the power supply and the coils L1 and L2, or thelike.

Embodiment 9

FIG. 14 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 9 of thepresent invention.

In the high-frequency magnetic field generating device in Embodiment 9,as shown in FIG. 14, the two coils L1 and L2 are connected in parallelwith each other, and one transmission line S1 s as a transmission linepart is connected to a connecting point between the two coils L1 and L2.In Embodiment 9, the one transmission line S1 s sets a currentdistribution so as to locate the two coils L1 and L2 at positions otherthan a node of a stationary wave.

Specifically, in Embodiment 9, as shown in FIG. 14, one end of the lineunit S1 s is connected through a first impedance matching unit 11 to thehigh-frequency power supply 1, and the other end of the line unit S1 sis connected to one connecting point between the two coils L1 and L2.Further, one end of a second impedance matching unit 11 is connected tothe other connecting point between the two coils L1 and L2. The otherend of the second impedance matching unit 11 is open-circuited.Therefore, microwave current flows from the high-frequency power supply1 through the first impedance matching unit 11 and the line unit S1 s tothe ends of the two coils L1 and L2. The two coils L1 and L2 haveidentical shapes to each other. Consequently, in view from thehigh-frequency power supply 1, (a) the coil L1 and the line unit S1 sand (b) the coil L2 and the line unit S1 s have identical high frequencycharacteristics (i.e. identical electrical lengths) to each other.

For example, if an electrical length of the coils L1 and L2 and the lineunit S1 s is LAMBDA/4 (LAMBDA: wavelength of the microwave), then acurrent distribution as shown in FIG. 14 appears, and the coils L1 andL2 are not located at any nodes of a stationary wave but located nearantinodes of a stationary wave; and consequently, sufficient microwavecurrent flows in the coils L1 and L2 and induces a magnetic field as amicrowave.

Embodiment 10

FIG. 15 shows a circuit diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 10 of thepresent invention.

In the high-frequency magnetic field generating device in Embodiment 10,as shown in FIG. 15, the two coils L1 and L2 are connected in parallelwith each other, and transmission lines S1 s as a transmission line partare connected to connecting points between the two coils L1 and L2,respectively. In Embodiment 10, the transmission lines S1 s set acurrent distribution so as to locate the two coils L1 and L2 atpositions other than a node of a stationary wave.

Specifically, in Embodiment 10, as shown in FIG. 15, one end of thefirst line unit S1 s is connected through a first impedance matchingunit 11 to the high-frequency power supply 1, and the other end of thefirst line unit S1 s is connected to one connecting point between thetwo coils L1 and L2. Further, one end of a second line unit S1 s isconnected to the other connecting point between the two coils L1 and L2.The other end of the second line unit S1 s is connected to one end of asecond impedance matching unit 11. The other end of the second impedancematching unit 11 is open-circuited. Therefore, microwave current flowsfrom the high-frequency power supply 1 through the first impedancematching unit 11 and the first line unit S1 s to the ends of the twocoils L1 and L2. The two coils L1 and L2 have identical shapes to eachother, and the line units S1 s also have identical shapes to each other.Consequently, in view from the high-frequency power supply 1, (a) thecoil L1 and the line units S1 s and (b) the coil L2 and the line unitsS1 s have identical high frequency characteristics (i.e. identicalelectrical lengths) to each other.

For example, if an electrical length of the coils L1 and L2 and the lineunits S1 s is LAMBDA/2 (LAMBDA: wavelength of the microwave), then acurrent distribution as shown in FIG. 15 appears, and the coils L1 andL2 are not located at any nodes of a stationary wave but located nearantinodes of a stationary wave; and consequently, sufficient microwavecurrent flows in the coils L1 and L2 and induces a magnetic field as amicrowave.

Embodiment 11

FIG. 16 shows a diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 11 of thepresent invention.

In Embodiment 11, the coils L1 and L2 are formed as metal patterns inparallel with each other on a front surface and a back surface of acircuit board 61 that has a predetermined thickness. Further, apenetrating hole 62 is formed so as to penetrate a center of the coilsL1 and L2. This penetrating hole 62 enables the high-frequency alternatemagnetic field to be applied to a sample not only (a) in a case that apair of the coil L1 and L2 is arranged at one side from the sample witha predetermined distance but (b) in a case that the sample is arrangedat any position between the coils L1 and L2 in the height direction.

Further, as shown in FIG. 16, penetrating holes 63 and 64 may be formedin the wall thickness of the circuit board 61 so as to be parallel to aradius direction of the coils L1 and L2. In such a case, a laser beamenters from the penetrating hole 63, a sample (not shown) in thepenetrating hole 62 is irradiated with the laser beam, and reflectionlight thereof passes through the penetrating hole 62 in an upwarddirection and/or a downward direction. Therefore, this reflection lightcan be detected by a microscope. Further, a part of the laser light beampasses through the sample and the part of the laser light beam exitsthrough the penetrating hole 64. Therefore, the exiting part of thelaser light beam may be observed. With talking refraction of the lightbeam into account, a diameter of the penetrating hole 64 may be largerthan a diameter of the penetrating hole 63.

In Embodiment 11, the circuit board 61 is arranged in between the coilsL1 and L2 in parallel, and therefore, an advantageous mechanicalcharacteristic and an advantageous electrical characteristic areobtained from various viewpoints such as stable forming of shapes of thecoils L1 and L2 and keeping a stable distance between the coils L1 andL2.

Embodiment 12

FIG. 17 shows a diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 12 of thepresent invention.

In Embodiment 12, the high-frequency magnetic field generating deviceincludes a plate coil La instead of the aforementioned coils L1 and L2described in Embodiment 11. A penetrating hole 82 is formed in a circuitboard 81 that has a predetermined thickness. The plate coil La isarranged in the penetrating hole 82. In Embodiment 12, the plate coil Lais fixed on an inner wall facing the penetrating hole 82 of the circuitboard 81 such that a longitudinal direction of a cross section of theplate coil La is perpendicular to the circuit board 81. The crosssection of the plate coil La has a substantially rectangle shape. Thepenetrating hole 82 may be a through hole; and the plate coil La may bea member formed by flexing and/or bending a thin metal plate such ascopper plate or may be a metal foil formed on an inner circumferentialsurface of the through hole as the penetrating hole 82 using metalplating or the like.

Further, in Embodiment 12, the penetrating hole 82 includes anobservation hole part 82 a of which a cross section has a circularshape. Among four edge line parts LaEU and LaEL (in particular, edgeline parts in the observation hole part 82 a) of the plate coil La, (a)one of edge line parts LaEU in a top end side and (b) one of edge lineparts LaEL in a bottom end side act as two coils arranged with apredetermined gap in parallel with each other, and these two coils arearranged (a) in between which electron spin resonance material isarranged or (b) arranged at one side from electron spin resonancematerial. The current intensively flows at the edge line parts LaEU andLaEL of the plate coil La due to skin effect in high frequency (inparticular, equal to or higher than MHz order), and therefore, the edgeline part LaEU in the top end side and the edge line part LaEL in thebottom end side substantially act as individual coils. It is favorablethat a height of the plate coil La (i.e. a length of a long side of thecross section) is set to be substantially equal to a radius of acircular part of the plate coil La. Further, in order to restrain straycapacitance between the plate coil La and a lens barrel of themicroscope, it is favorable that a width of the plate coil La (i.e. alength of a short side of the cross section) is set to be sufficientlysmaller than the height of the plate coil La.

This penetrating hole 82 enables the high-frequency alternate magneticfield to be applied to a sample not only (a) in a case that both of theedge line part LaEU in the top end side and the edge line part LaEL inthe bottom end side are arranged at one side from the sample with apredetermined distance but (b) in a case that the sample is arranged atany position between the edge line part LaEU in the top end side and theedge line part LaEL in the bottom end side in the height direction.

Further, as shown in Embodiment 17, penetrating holes 83 and 84 may beformed in the wall thickness of the circuit board 81 so as to beparallel to a radius direction of the circular part of the plate coilLa, and penetrating holes 85 a and 85 b of the plate coil La may beformed at positions on an extension line between the penetrating holes83 and 84. In such a case, a laser beam enters from the penetratingholes 83 and 85 a, a sample (not shown) in the penetrating hole 82 isirradiated with the laser beam, and reflection light thereof passesthrough the penetrating hole 82 in an upward direction and/or a downwarddirection. Therefore, this reflection light can be detected by amicroscope. Further, a part of the laser light beam passes through thesample and the part of the laser light beam exits through thepenetrating holes 85 b and 84. Therefore, the exiting part of the laserlight beam may be observed. With talking refraction of the light beaminto account, diameters of the penetrating holes 85 a and 84 may belarger than diameters of the penetrating holes 83 and 85 a.

Other parts of configuration and behaviors of the high-frequencymagnetic field generating device in Embodiment 12 are identical orsimilar to those in Embodiment 9 or 11 or a combination thereof, andtherefore not explained here.

As mentioned, in Embodiment 12, the aforementioned plate coil La isapplied and thereby a direct-current resistance of the coil gets low. Ifthere is a metallic object such as a housing of the microscope forobservation or a dielectric object such as sample base around the coil,then the resonance frequency may change due to the existence of suchobject, but such change of the resonance frequency is restrained byapplying the aforementioned plate coil La.

For example, when the thickness of the circuit board was 1.6 mm and aradius of the circular part of the plate coil La was 2 mm, the resonancefrequency in Embodiment 12 was 2.96 GHz in a status that a sample wasarranged in the penetrating hole 82 or 2.965 GHz in a status that a lensof the microscope was arranged at the distance of 1.5 mm. Contrarily, ina comparative example, the resonance frequency was 2.84 GHz in a statusthat a sample was arranged in the penetrating hole or 2.89 GHz in astatus that a lens of the microscope was arranged at the distance of 1.5mm. Thus, the change of the resonance frequency is restrained.

Embodiment 13

FIG. 18 shows a diagram that indicates a configuration of ahigh-frequency magnetic field generating device in Embodiment 13 of thepresent invention.

In Embodiment 13, the penetrating hole 82 has a substantiallyrectangular shape, and the plate coil La is arranged in the penetratinghole 82.

In Embodiment 13, the plate coil La is fixed such that the plate coil Laprotrudes from an inner wall facing the penetrating hole 82 of thecircuit board 81.

Other parts of configuration and behaviors of the high-frequencymagnetic field generating device in Embodiment 13 are identical orsimilar to those in Embodiment 12, and therefore not explained here.

In addition, about various changes for the form of the above-mentionedenforcement and the correction, it is apparent to these skilled in theart. Such a change and the correction may be performed without leavingthe purpose of the subject and the range and without weakening anadvantage aimed at. In other words such a change and a correction intendto be within the range of the request.

For example, in any of the aforementioned embodiments, the ends of theaforementioned two line units may be neither open-circuited norshort-circuited, and may be terminated with a predetermined resistancevalue.

Further, in Embodiment 4, the coils L11 and L21 may be removed and theline units S11 and S21 may be connected to each other, and thehigh-frequency power supply 1 may be connected to a connecting pointbetween the line units S11 and S21.

Furthermore, in any of the aforementioned embodiments, the line unit isused as the transmission line unit. Alternatively, the aforementionedline unit may be replaced with a lumped constant circuit if required.

Furthermore, in any of the aforementioned embodiments, a diamondincluding an NVC is described as an example of the ODMR material.Alternatively, the ODMR material including another color center (e.g.SiC color center or color center of ZnO, GaN, Si, an organic substanceor the like) may be used. In such a case, the high-frequency powersupply 1 generates microwave current having a frequency corresponding tothe color center in use.

Furthermore, in any of the aforementioned embodiments, thehigh-frequency magnetic field generating device can form a uniformmagnetic field in an area substantially identical to an opening area ofthe coil. Therefore, in particular, the high-frequency magnetic fieldgenerating device is applied to ODMR in a high frequency range equal toor higher than 100 MHz, and in addition, the high-frequency magneticfield generating device may be applied to another measurement usingelectron spin resonance, such as EDMR. FIG. 19 shows a diagram thatindicates a result of a simulation of a magnetic field emitted from thehigh-frequency magnetic field generating device in Embodiment 6 of thepresent invention. This simulation is performed under a condition thatcurrent of about 3 GHz is supplied from a power supply to the coil L1and L2, and the result shows that as shown in FIG. 19, a uniformmagnetic field (for example, a magnetic field area that has an error of10 percent or less of the value of the magnetic field intensity at thecenter) are generated in a substantially whole area of the opening areafrom the center of the circular part of the coils L1 and L2.

Further, even in a range less than 100 MHz, a high-frequency magneticfield generating device in each embodiment of the present invention canbe used as well as an ordinary coil-type resonator.

INDUSTRIAL APPLICABILITY

For example, the present invention is applicable to a high-frequencymagnetic field generating device for Optically Detected MagneticResonance.

What is claimed is:
 1. A high-frequency magnetic field generatingdevice, comprising: a plate coil; and a high-frequency power supply thatgenerates microwave current that flows in the plate coil; wherein (a)one edge line part in a top end side and (b) one edge line part in abottom end side among four edge line parts of the plate coil act as twocoils arranged with a predetermined gap in parallel with each other, thetwo coils (a) in between which electron spin resonance material isarranged or (b) arranged at one side from electron spin resonancematerial.
 2. The high-frequency magnetic field generating deviceaccording to claim 1, further comprising a circuit board; wherein alongitudinal direction of a cross section of the plate coil isperpendicular to the circuit board.
 3. The high-frequency magnetic fieldgenerating device according to claim 1, further comprising: a circuitboard; and a penetrating hole in the circuit board; wherein the platecoil is arranged in the penetrating hole.
 4. The high-frequency magneticfield generating device according to claim 1, further comprising atransmission line part connected to the two coils, that sets a currentdistribution so as to locate the two coils at positions other than anode of a stationary wave.
 5. The high-frequency magnetic fieldgenerating device according to claim 1, wherein the plate coil comprisesa circular part, and a penetrating hole formed in the circular part; andthe penetrating hole is formed such that a light beam with which theelectron spin resonance material is irradiated passes through thepenetrating hole.
 6. The high-frequency magnetic field generating deviceaccording to claim 1, wherein the plate coil comprises a circular part,and two penetrating holes formed in the circular part; and the twopenetrating holes are formed such that a light beam with which theelectron spin resonance material is irradiated enters from one of thetwo penetrating holes, and the light beam exits through the other of thetwo penetrating holes.